Basic usage
null instanceof Object 为false；
null instanceof any class is false;
the corresponding class or parent class of any instance instanceof is true;The basic data type instanceof Object will report an error when compiling (such as int a; a instanceof Object cannot be compiled), because the basic data type is not an instance of any class
The difference between instanceof and getClass
public class Test
{
public static void testInstanceof(Object x)
{
System.out.println("x instanceof Parent: "+(x instanceof Parent));
System.out.println("x instanceof Child: "+(x instanceof Child));
System.out.println("x getClass Parent: "+(x.getClass() == Parent.class));
System.out.println("x getClass Child: "+(x.getClass() == Child.class));
}
public static void main(String[] args) {
testInstanceof(new Parent());
System.out.println("---------------------------");
testInstanceof(new Child());
}
}
class Parent {
}
class Child extends Parent {
}
/*
output:
x instanceof Parent: true
x instanceof Child: false
x getClass Parent: true
x getClass Child: false
---------------------------
x instanceof Parent: true
x instanceof Child: true
x getClass Parent: false
x getClass Child: true
*/
As can be seen from the program output, the type checking rules of instanceof are: do you belong to this class? Or do you belong to a derived class of that class? Obtaining type information through getClass and using == to check for equality is a strict judgment. There will be no inheritance considerations